In rotary electric machines, the occurrence of damage to a stator coil due to excessive temperature increases has been prevented by installing a temperature detecting element that detects a temperature of the stator coil in a stator, and controlling an excitation current flowing to the stator coil based on the temperature detected by the temperature detecting element.
In the conventional electric motor that is described in Patent Literature 1, for example, an insulator that includes: a hollow tube portion; an inner end portion that is linked to one end of the tube portion; and an outer end portion on which a pair of coil grooves are formed that are linked to another end of the tube portion, and that extend in an axial direction in a vicinity of one side portion that is linked to the tube portion, is mounted such that a coil supporting portion of a tooth is passed through the tube portion, and the inner end portion and the outer end portion are pressed by a tip end portion and a yoke segment of the tooth. The stator coil is configured such that a conductor wire is wound onto the tube portion so as to pass through one coil groove, and the temperature detecting element is disposed so as to be able to detect the temperature of the stator coil by being press-fitted into the other coil groove.
However, in the conventional electric motor that is described in Patent Literature 1, because the outer end portion on which the coil grooves are formed is positioned on an inner circumferential side of the yoke segment, one problem has been that winding space inside the slots is reduced, reducing coil space factor, and making increases in output unachievable. Furthermore, because the temperature detecting element has a larger diameter than the conductor wire, and it is necessary to increase the wall thickness of the outer end portion to ensure the groove depth of the coil groove if the coil groove is used to hold the temperature detecting element, winding space inside the slots is further reduced, reducing coil space factor.
In addition, in the conventional electric motor that is described in Patent Literature 1, because the coil grooves are formed so as to extend in an axial direction in a vicinity of one side portion that is linked to the tube portion, the temperature detecting element that is inserted into the coil groove detects the temperature of a side of the stator coil near the tube portion, i.e., a coil inner layer portion. Because the temperature of the stator core is lower than the temperature of the stator coil, the temperature of the coil inner layer portion is generally lower than the temperature of a coil outer layer portion. Consequently, one problem has been that the temperature detecting element cannot detect the temperature of the coil outer layer portion of the stator coil, which is what should be controlled.
In consideration of such conditions, conventional stators have been proposed in which a trunk portion is disposed by inserting a rod-shaped portion into a gap between a coil end and a tooth from an inner circumferential side to hold a temperature detecting element such that the trunk portion contacts a surface of the coil end on the inner circumferential side (see Patent Literature 2, for example).